Pipes are used to transmit large volumes of fluid. In order to control flow of fluid through these pipes, valves are commonly used at specific points in the piping or between different pipes. The valves used typically include a valve seat and a valve stem moved relative to the valve seat.
The position of the valve stem affects the flow of the fluid through the pipe. In a two-way valve, the flow is restricted when the valve stem is positioned so that a valve disk, a gate, a blocking member or piston is seated in the valve seat. Alternatively, the flow is least restricted when the valve stem is positioned such that the piston is located away from the valve seat. Intermediate positions are also available depending on the position of the valve stem and, hence, the valve disk.
Similarly, in three-way and four-way valves, the position of the valve stem determines the fluid flow. This fluid flow is restricted to flowing along a first path when the piston seats in the first valve seat. Alternatively, the fluid flow is restricted to flowing along a second path when the piston seats in a second valve seat.
For larger pipes, the valve stems are correspondingly large and heavy.
Many prior art devices use rising stem actuators for vertical control of these valve stems. However, vertical movement of these known valve stems often requires great amounts of force and such vertical movement is particularly difficult to implement. A means to substitute, convert, or transfer this force into a lesser force or motion is therefore desired. Thus, there is a need to replace currently available rising stem actuators with an actuator which requires less force input to achieve the same amount of force output as known actuators.
In addition, there is a need for an actuator which has a greater variety of applications than known actuators.